针对退化型失效的复杂装备系统,提出基于隐图解评审技术(hidden graphic evaluation and review technique,HGERT)网络模型来进行系统可靠性预计和评估的方法。图解评审法(graphic evaluation and review technique,GERT)网络中的节点...针对退化型失效的复杂装备系统,提出基于隐图解评审技术(hidden graphic evaluation and review technique,HGERT)网络模型来进行系统可靠性预计和评估的方法。图解评审法(graphic evaluation and review technique,GERT)网络中的节点代表装备失效过程中正常状态到失效状态的转移,通过传感器将反映系统隐性状态的性能特征参数进行量化输入,从而将GERT网络中的各个劣化状态节点进行展开。应用Viterbi算法对模型参数进行解码和学习,确定退化型失效系统状态转移概率。将装备运行中所处的工作应力、环境载荷等影响性能衰退的因素作为输入,将关键性能指标退化量作为输出,建立装备性能退化的一般控制模型并将其作为GERT网络活动传递的随机变量。借助于信号流图理论对参数进行解析,监测系统处于不同状态时的性能退化水平,为故障预测和装备健康管理提供支持。案例通过对铣床性能退化量的分析,证明所构模型的可行性和合理性。展开更多
A thrust estimator with high precision and excellent real-time performance is needed to mitigate perfor- mance deterioration for future aero-engines. A weight least squares support vector regression is proposed using ...A thrust estimator with high precision and excellent real-time performance is needed to mitigate perfor- mance deterioration for future aero-engines. A weight least squares support vector regression is proposed using a novel weighting strategy. Then a thrust estimator based on the proposed regression is designed for the perfor- mance deterioration. Compared with the existing weighting strategy, the novel one not only satisfies the require- ment of precision but also enhances the real-time performance. Finally, numerical experiments demonstrate the effectiveness and feasibility of the proposed weighted least squares support vector regression for thrust estimator. Key words ： intelligent engine control; least squares ; support vector machine ; performance deterioration展开更多
In order to avoid severe performance degradation led by the inter-cell interference (ICI) in orthogonal frequency division multiple access (OFDMA) systems with a frequency reused factor (FRF) of 1,distributed schedule...In order to avoid severe performance degradation led by the inter-cell interference (ICI) in orthogonal frequency division multiple access (OFDMA) systems with a frequency reused factor (FRF) of 1,distributed schedule algorithm (DS-OCS) and distributed proportional fairness schedule algorithm (DPFS-OCS) based on orthogonal complement space (OCS) were proposed. The first right and left singular vectors of the channel that the user experienced were selected as the transmitting and receiving beamforming vectors. An interference space was spanned by the left singular vectors of the entire interference users in the same channel. The most suitable user lay in the OCS of the interference space was scheduled to avoid suffering interference from neighboring cells based on the criterion of system capacity maximizing and proportional fairness. The simulation results show that the average system capacity can be improved by 2%-4% compared with the DS-OCS algorithm with the Max C/I algorithm,by 6%-10% compared with the DPFS-OCS algorithm with the PF algorithm.展开更多
文摘针对退化型失效的复杂装备系统,提出基于隐图解评审技术(hidden graphic evaluation and review technique,HGERT)网络模型来进行系统可靠性预计和评估的方法。图解评审法(graphic evaluation and review technique,GERT)网络中的节点代表装备失效过程中正常状态到失效状态的转移,通过传感器将反映系统隐性状态的性能特征参数进行量化输入,从而将GERT网络中的各个劣化状态节点进行展开。应用Viterbi算法对模型参数进行解码和学习,确定退化型失效系统状态转移概率。将装备运行中所处的工作应力、环境载荷等影响性能衰退的因素作为输入,将关键性能指标退化量作为输出,建立装备性能退化的一般控制模型并将其作为GERT网络活动传递的随机变量。借助于信号流图理论对参数进行解析,监测系统处于不同状态时的性能退化水平,为故障预测和装备健康管理提供支持。案例通过对铣床性能退化量的分析,证明所构模型的可行性和合理性。
基金Supported by the National Natural Science Foundation of China(51006052)the Nanjing University of Science and Technology Outstanding Scholar Supporting Program~~
文摘A thrust estimator with high precision and excellent real-time performance is needed to mitigate perfor- mance deterioration for future aero-engines. A weight least squares support vector regression is proposed using a novel weighting strategy. Then a thrust estimator based on the proposed regression is designed for the perfor- mance deterioration. Compared with the existing weighting strategy, the novel one not only satisfies the require- ment of precision but also enhances the real-time performance. Finally, numerical experiments demonstrate the effectiveness and feasibility of the proposed weighted least squares support vector regression for thrust estimator. Key words ： intelligent engine control; least squares ; support vector machine ; performance deterioration
基金Projects(2009ZX03003-003, 2009ZX03003-004) supported by the Major National Science & Technology ProgramProject(B08038) supported by the "111" Project+1 种基金Project(HX0109012417) supported by Huawei Technologies Co., Ltd, ChinaProject(IRT0852) supported by Program for Changjiang Scholars and Innovative Research Team in Chinese University
文摘In order to avoid severe performance degradation led by the inter-cell interference (ICI) in orthogonal frequency division multiple access (OFDMA) systems with a frequency reused factor (FRF) of 1,distributed schedule algorithm (DS-OCS) and distributed proportional fairness schedule algorithm (DPFS-OCS) based on orthogonal complement space (OCS) were proposed. The first right and left singular vectors of the channel that the user experienced were selected as the transmitting and receiving beamforming vectors. An interference space was spanned by the left singular vectors of the entire interference users in the same channel. The most suitable user lay in the OCS of the interference space was scheduled to avoid suffering interference from neighboring cells based on the criterion of system capacity maximizing and proportional fairness. The simulation results show that the average system capacity can be improved by 2%-4% compared with the DS-OCS algorithm with the Max C/I algorithm,by 6%-10% compared with the DPFS-OCS algorithm with the PF algorithm.
